16 BULLETIN 705, U. S. DEPARTMENT OF AGRICULTURE. 
RELATION OF CLOVER TO CROP YIELDS. 
Of the leguminous crops grown on the silt loam farms, clover was 
by far the most important, with vetch second. In Table XII the 
farms are arranged in groups according to the percentage of the field- 
crop area devoted to clover. 
60 
50 
40 
O 30 
z 
o 
20 
10 
s 
WHEAT 
/ / 
// 
// 
/ 
/ 
/ 
r 
12 26 44.3 
AVERAGE PERCENTAGE OF FIELD CROPS IN LEGUMES 
Fig. 4. — Percentage of increase in crop yields with increase in percentage of field crop 
area in legumes on 144 silt loam farms in Marion and Polk Counties, Oreg. (1912). 
Table XII. — Relation of percentage of field-crop area in clover to crop yields on 144 silt 
loam soil farms, Marion and Polk Counties, Oreg. {1312). 
Item. 
All 
farms. 
Per cent of field-crop area 
in clover. 
No 
clover. 
Less 20 or 
than 20. more. 
Number of farms 
Average per cent of field-crop area in clover 
Crop yields per acre: 
Potatoes (bushels) 
Wheat (bushels) 
Oats (bushels) 
Hay (tons) 
Crop index 
144 
12.0 
150.2 
22.0 
37.7 
1.94 
100 
61 
140.4 
20.5 
34.1 
1.82 
92 
45 
11.1 
159.0 
22.1 
38.2 
2.00 
102 
38 
32.7 
163.7 
24.9 
45.5 
2.05 
113 
